Conventionally, there are hybrid vehicles. For example, Patent Document 1 discloses a technology of a drive system of a hybrid vehicle including a speed changing mechanism that changes the speed of rotation of an internal combustion engine and transmits the rotation to a power distribution mechanism, a first transmission shaft that transmits power from the internal combustion engine to the speed changing mechanism, and a second transmission shaft that transmits power delivered from the speed changing mechanism to the power distribution mechanism. In the drive system of the hybrid vehicle of Patent Document 1, the speed changing mechanism has a differential mechanism in which two sets of planetary gear units are combined, a first brake B1 that can stop rotation of a ring gear R1 of the differential mechanism, a second brake B2 that can stop rotation of a ring gear R2, and a clutch C that permits or inhibits power transmission from the first transmission shaft to the ring gear R1.